I have 2 patient groups: one with right hemisphere lesion, another with left hemisphere lesion
I want to flip lesion side to right hemisphere, then I can do grand average of all the patient
(That means the group with left hemisphere lesion have to mirror their MEG source signals)
This is a common process in fMRI study, but not provided in Brainstorm yet
So, is it possible to flip MEG source signal or sensor signal?
Thanks a lot !
Hello
No, there is currently no way to flip the MEG recordings left/right in Brainstorm.
I’m not sure how to do this operation properly, I never though about it. It sounds difficult, but if you are very motivated and if you have some time to dedicate to it, it’s probably doable.
If you want to do it manually and if you have a Matlab license, you can access all the information in the Brainstorm database and modify it to match your objectives. Everything is saved in Matlab .mat files, you can read/write them with the load/save function from Matlab, or use the popup menus “File > Export to Matlab” and “File > Import from Matlab”.
If you want to modify the sensor positions: change the the fields .Loc and .Orient in the channel file.
If you want to modify the recordings: change the field .F in the data files
If you want to modify the position of the sources: change the fields .Vertices and delete the field VertNormals in the cortex file + modify the field GridLoc in the source file (if it’s not empty) => This approach would work only with Full source files (not kernel-based, see the source tutorials) + you have to use an individual anatomy for every subject, and re-interpolate the source values on the template brain after this flip. I’m not sure how to do all this.
Maybe there are many problems with any of this approach, I can’t promise that anything would work.
Cheers,
Francois